In general, RF (radio frequency) systems typically utilize some type of antenna structure for wireless communication. For frequencies up to 60 GHz, an antenna structure is designed separately from a radio frequency integrated circuit (RFIC) package, and then connected to the RFIC package. In particular, with this technique, an antenna structure, whether a single antenna or an antenna array, can be connected to the RFIC package using cables with connectors or using bonding wires.
For millimeter-wave frequencies in a range of 60 GHz to 94 GHz, an antenna can be implemented in an antenna-in-package that includes and RFIC die, and one or more antenna structures and associated antenna feed lines, wherein the antenna structure is attached to the RFIC die. This technique eliminates the need to use a bonding wire as the antenna feed line, thereby resulting in reduced power loss and reduced antenna impedance mismatch due to the extra inductance from the bonding wire. With this design, the antenna-in-package is an RFIC package, as the antenna-in-package includes not only the antenna structure, but also all the low frequency components, such as power plane, base band signal lines, control lines, DC power supply line, etc. The antenna-in-package is attached to an application board typically through BGA balls.
For operating frequencies above 94 GHz, however, it is not trivial to design and manufacture antenna-in-package structures due to the lack of availability of proper antenna substrates and the limitations of currently available processing technologies that do not afford the requisite manufacturing resolutions for such high-frequency applications. Furthermore, a standard interface between the antenna package and the RFIC die (typically a flip-chip connection) produces more than 1 dB signal attenuation at 94 GHz, minimizing the advantages of antenna-in-package designs.